The present invention relates to electrical components, and more particularly the structural design of the connections of lightning arresters having bowl-shaped electrodes which are soldered to a tubular ceramic insulator.
In gas-filled lightning arresters having bowl-shaped copper electrodes, the use of copper as the electrode material offers the advantages of small dimensions and high current carrying capacity. The electrodes can be manufactured by an extrusion or embossing method. Because of the considerable differences in coefficients of thermal expansion of copper and ceramic, the electrodes have a wall thickness of less than 0.6 mm in the vicinity of the soldered connections with the ceramic insulator. Thermal stresses can therefore be compensated by the plastic deformability of the copper. Connection of copper electrodes in the axial direction is either performed positively by the edge provided for soldering with the ceramic insulator or integrally by connecting wires welded to a stub in the rear bottom area of the electrode surface itself (as seen in U.S. Pat. No. 4,266,260, and U.S. Pat. No. 4,433,354). Connecting wires soldered in this way can also be bent radially (as seen in U.S. Pat. No. 4,866,563). Radial connection of connecting wires requires a certain amount of space in the axial direction that is not always available when lightning arresters are mounted in electronic equipment. In these cases, axial contacts cannot be used. This type of electrode contact likewise cannot be used when the electrodes are fitted axially with an auxiliary device such as an overload protector. In these cases the electrodes can be provided with radially welded connecting wires, provided the electrode edge has sufficient wall thickness, as is usual in electrodes made of an iron alloy otherwise conventionally used for this purpose (see U.S. Pat. No. 4,984,125).
As shown in German Patent Application No. P 43 18 366.2, a terminal is connected integrally, endwise with the soldering edge of a copper electrode; the terminal has the shape of a ring in this area. The ring and the radially projecting connecting wire are made integral. The ring simultaneously serves to center an additional cylindrical component.
In a gas-filled lightning arrester having two bowl-shaped copper electrodes soldered by their edges endwise on a tubular ceramic insulator, there is a need for a contact on the copper electrode that discharges axially to the smallest degree possible and can be readily manufactured.